The Influence of Cooling Rate During Crystallization on the Effective Partitioning Coefficient in High-Entropy Alloys from Al-Ti-Co-Ni-Fe System

Lü

Materials Science and Technology

et al. 2019

Homogenisation has been used to eliminate solute segregation of CrMnFeCoNi high-entropy alloys (HEAs) before thermomechanical processing. To overcome the deficiencies caused by high-temperature homogenisation, we cancelled the homogenisation and studied the solute segregation feature and its effect on the grain growth and the mechanical property. The HEA forms equiaxed grains with the solute segregation in the range of tens of micrometres after cold rolling and recrystallisation. The grain growth in recrystallisation still abides by the classical grain growth kinetics, but with a higher power index of 3.33 and activation energy of 392.4 kJ mol−1 than those of the homogenised HEA, indicating a solute-drag effect. The relationship between the yield stress and grain size follows the Hall–Petch dependence with a higher intrinsic strength.

Section: Introductionmentioning

confidence: 99%

Solute segregation effect on grain boundary migration and Hall–Petch relationship in CrMnFeCoNi high-entropy alloy

Lü

Materials Science and Technology

et al. 2019

“…In our previous paper [ 24 ], we showed that, in HEAs in as-cast state, there can be large differences in the chemical composition of dendrites and interdendritic regions. These differences can be reduced by annealing, which we proved on the example of the M4 alloy, in which the elemental distribution after annealing was homogeneous ( Figure 2 ).…”

Section: Resultsmentioning

confidence: 99%

“…Assuming a solid solution could be achieved in such an alloy, the yield strength would be slightly higher than in the M3 or M4 alloy, i.e., 353 MPa. As we showed in our previous work [ 24 ], producing such an alloy with a solid solution structure is impossible. A system of two disordered solid solutions of FCC and BCC, with numerous precipitates of brittle intermetallic phases, was formed.…”

Section: Discussionmentioning

confidence: 96%

The Effect of Al and Ti Additions on Solid Solution Strengthening and Precipitation Hardening in CoNiFe Medium-Entropy Alloys

Bała,

Górecki,

Dziurka

et al. 2023

Materials

Self Cite

The effect of Al and Ti additions on the microstructure and properties of CoNiFe alloys was studied in this paper. The investigations were conducted on four specially designed and produced arc furnace alloys (from 3 to 5 components, with medium to high entropy). Samples in various states were analyzed, i.e., as-cast, after homogenization, after solution heat treatment, and after solution heat treatment and aging. The obtained samples were characterized by: SEM observations, EDS, XRD, TEM analyses, and finally, hardness measurements. The solid solution strengthening coming from the addition of 5 at. pct. Al was negligible, while the effect from the 5 at. pct. of Ti addition was significant. The precipitation hardening effect related to the presence of the (CoNi)3Ti phase caused by the Ti addition is comparable with the total effect of the Al and Ti addition, which caused the precipitation of (NiCo)3AlTi.

Archives of Metallurgy and Materials

“…However, it should be emphasized that in general the VEC parameter enables the prediction of the type of expected crystallographic structure, but it does not allow to design solid state solutions . It s hould be noticed than even if ΔH mix , δ and Ω conditions are fulfilled it is possible that in the material in some systems could exist microsegregation [18].…”

Section: Discussionmentioning

confidence: 99%

Necessary Thermodynamics Factors to Obtain Simple Solid Solutions in High-Entropy Alloys from the Al-Ti-Co-Ni-Fe System

Górecki

Bała

Kozieł

et al. 2017

In this paper findings regarding the design and synthesis of High-Entropy Alloys based on mixing enthalpy, mixing entropy, δ parameter, Ω parameter and valence electron concentration are presented. Four alloys were synthesised with different predicted crystalline structures. Results of the microstructure and crystal structure studies are presented. It was shown that predicted structures as well as complex intermetallic phases exist in the material. The validity of valence electron concentration as well as additional parameters such as mixing enthalpy, mixing entropy and others necessary to obtain only the solid solution in High-Entropy Alloys were examined.